单项选择题

Color is very important to most animals for it helps them to get along in the world. Color (31) to make an animal difficult for its enemies to see. Many animals match their (32) so well that as long as they do not move no one is (33) to see them. You probably have often "jumped" a rabbit. If you (34) , you know how the rabbit sits perfectly still (35) you are just a few feet away. You (36) see the rabbit till it runs for its (37) matches very closely the place where it is (38) Many times you may have walked past a rabbit (39) didn’t run and you never knew it was there at all. One of the most usual color schemes that helps animals to keep (40) being seen, is a dark back and light underpants, if an animal is the same color all over, there is always a dark shadow along the animal’s belly (腹部). Even if an enemy couldn’t see the animal he could see this dark shadow.